[PATCH net-next v5 3/3] net: macb: Optimize reading HW timestamp

[Harini Katakam]

From: Harini Katakam <harini.katakam@xxxxxxxxxx>

The seconds input from BD (6 bits) just needs to be ORed with the
upper bits from timer in this function. Avoid addition operation
every single time. Seconds rollover handling is left untouched.

Signed-off-by: Harini Katakam <harini.katakam@xxxxxxxxxx>
Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxxxxx>
---
v5 and v4:
No change
v3:
No change
v2:
- Update HW timestamp logic to remove sec_rollover variable as per
Cladiu's comment
- Remove Richard Cochran's ACK on original patch as the patch changed

 drivers/net/ethernet/cadence/macb_ptp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/cadence/macb_ptp.c b/drivers/net/ethernet/cadence/macb_ptp.c
index f962a95068a0..51d26fa190d7 100644
--- a/drivers/net/ethernet/cadence/macb_ptp.c
+++ b/drivers/net/ethernet/cadence/macb_ptp.c
@@ -258,6 +258,8 @@ static int gem_hw_timestamp(struct macb *bp, u32 dma_desc_ts_1,
 	 */
 	gem_tsu_get_time(&bp->ptp_clock_info, &tsu, NULL);
 
+	ts->tv_sec |= ((~GEM_DMA_SEC_MASK) & tsu.tv_sec);
+
 	/* If the top bit is set in the timestamp,
 	 * but not in 1588 timer, it has rolled over,
 	 * so subtract max size
@@ -266,8 +268,6 @@ static int gem_hw_timestamp(struct macb *bp, u32 dma_desc_ts_1,
 	    !(tsu.tv_sec & (GEM_DMA_SEC_TOP >> 1)))
 		ts->tv_sec -= GEM_DMA_SEC_TOP;
 
-	ts->tv_sec += ((~GEM_DMA_SEC_MASK) & tsu.tv_sec);
-
 	return 0;
 }
 
-- 
2.17.1